1. Technical Field
This disclosure relates to an over-voltage protection circuit and an over-voltage protection method, and in particular, to an over-voltage protection circuit and an over-voltage protection method that can effectively prevent false operation of an upper bridge power switch.
2. Related Art
A switching voltage converting circuit is a voltage converting circuit. The switching voltage converting circuit manipulates, in a manner of switching a power switch, energy stored in an inductive element to supply the energy to an output load and converts an input voltage into an output voltage at an output end, so as to maintain a fixed output voltage value, and provide a load current required by the output load. The switching voltage converting circuit has high conversion efficiency, and therefore can decrease unnecessary heat generation, thereby reducing complexity on the heat dissipation design.
However, a power element in the switching voltage converting circuit often has to directly bear a high voltage, thereby possibly causing damage to the power element. In an application, in which high voltage input is converted into low voltage output, of the switching voltage converting circuit, usually, because an upper bridge power element directly bearing a high voltage is damaged, a channel thereof short-circuits, so that an output end directly bears a high voltage of the input end. In some power supply applications, a load connected to the output end is quite expensive component such as a central processing unit or an application processor. As a result, if power supply units of these components do not have an over-voltage protection mechanism, direct damage will be easily caused, thereby increasing maintenance costs.
As described above, because an upper bridge power switch directly bears the input high voltage, damage is easily caused due to an inappropriate input voltage. In addition, wrong control over the upper bridge power switch also easily and directly incurs an over-voltage threat on other circuit sections. Therefore, how to provide an effective over-voltage protection mechanism for the upper bridge power switch becomes a significant problem in the over-voltage protection design of the switching voltage converting circuit.